If you open the thumbnail it scrolls together with the main window! And this is all drawn on the serve side.
I changed a couple of things to remove the statics and the native text renderer to draw the string to use only GDI2 without creating the HDC.
This app also uncovered what I call an “edge bug”, a bug at the border line of the performance limits of Wisej. Internally the client wisej middleware queues all events and processes the queue at 75ms intervals in order to pack more data in a single message. The low interval (80ms) set in the app caused the scheduler to go into an infinite loop of canceling and rescheduling when adding more streams or more windows.